A question about kinematic transformations
02 Jun 2015 17:38 #59340
by anarchos
A question about kinematic transformations was created by anarchos
I am in the planning stages of building a 2D CNC "wire" bender, to bend ski/snowboard edges. My design has the X axis as a driven wheel that forces the edges through two non-driven wheels that move on the Y axis. I'd like to stay away from custom G-Code generation so that I am not locked into a single solution for generating the code, as I use a number of different programs/post processors.
So basically, whether the gcode is calling for X movements either forward or backwards, the driven wheel will need to continue in the same direction, with the Y axis making transformations based on the position of the X axis.
A very basic use scenario is being a square in gcode. X would move up(+), then Y would move to the right (+), X would move down(-), Y would move across to the left(-). I would need my machine to take that code and translate any X- movements into X+ movements, while "flipping the polarity" of the Y axis to take that into account. I hope that makes sense, I'm having a bit of trouble articulating my idea!
Would a custom kinematics setup be the best way to do this or am I barking up the wrong tree?
So basically, whether the gcode is calling for X movements either forward or backwards, the driven wheel will need to continue in the same direction, with the Y axis making transformations based on the position of the X axis.
A very basic use scenario is being a square in gcode. X would move up(+), then Y would move to the right (+), X would move down(-), Y would move across to the left(-). I would need my machine to take that code and translate any X- movements into X+ movements, while "flipping the polarity" of the Y axis to take that into account. I hope that makes sense, I'm having a bit of trouble articulating my idea!
Would a custom kinematics setup be the best way to do this or am I barking up the wrong tree?
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02 Jun 2015 23:20 #59351
by andypugh
The latter, I am afraid.
The problem is that kinematics has no idea what has happened previously, all it knows how to do is convert a set of instantanoues positions in space into actuator positions.
I think that your application would be better served by an input filter. That could convert the 2D path into a set of forward moves an left-right turns (which is basically what you need)
I think the filter is easy, as effectively _any_ straight move is a straight X move with no Y offset and any radius move (G2 G3) is a straight X move where the Y offset = R.
Replied by andypugh on topic A question about kinematic transformations
Would a custom kinematics setup be the best way to do this or am I barking up the wrong tree?
The latter, I am afraid.
The problem is that kinematics has no idea what has happened previously, all it knows how to do is convert a set of instantanoues positions in space into actuator positions.
I think that your application would be better served by an input filter. That could convert the 2D path into a set of forward moves an left-right turns (which is basically what you need)
I think the filter is easy, as effectively _any_ straight move is a straight X move with no Y offset and any radius move (G2 G3) is a straight X move where the Y offset = R.
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